Shot peening apparatus



Aug. 25, 1959 M. o. BLACKBURN 2,900,765

SHOT PEENING APPARATUS Fig;

Inches 0 INVENTOR.

. BY Mac/r 0. B/ac/rbum F ig, 3 D. c 5% His Al/omey Aug. 25, 1959 M. o.BLACKBURN 2,900,765

SHOT PEENING APPARATUS Filed June 10, 1957 2 Sheets-Sheet 2 ii I 22 i I6'3 m 63 1 "s2 60 2" INVENTOR.

t 7| BY Mac/r 0. Blackburn ig. 5 Z). G 5% H13 Attorney Patented Aug. 25,1959 ice SHOT PEENING APPARATUS Application June 10, 1957, Serial No.664,726

11 Claims. Cl.'519) This invention pertains to centrifugal blastingapparatus, and particularly to a centrifugal propelling machine forselective shot peening.

Heretofore centrifugal throwing apparatus has been designed foraccelerating and throwing particulate materials from the periphery of awheel against an object' to be worked, cleaned or abraded. Theparticulate mate rials which are impinged against an object can take theform of metallic shot or grit, sand and similar nonmetallic abrasives.Moreover, it has been proposed to control the direction in which theparticulate material is thrown and the length of the path swept by theparticulate material. However, in some instances it is desirable to workharden a given area of an object to varying degrees, that is, to workharden a portion of the area of an object to a predetermined degree ofhardness and graduate the work hardening on other portions of theobject. The present invention relates to apparatus for automaticallyselectively shot peening an object to concentrate the work hardening ina particular area and graduate the work hardening over other portions ofthe object. Accordingly, among my objects are the provision of meanswhereby thrown particulate material will be distributed over a path ofpredetermined area with a concentration at a portion of the area of thepath; the further provision of a throwing wheel having a plurality ofradially arranged slots with peripheral discharge openings of differentcross-sectional areas; the still further provision of throwing apparatusincluding means for regulating the rate of flow of particulate materialtherethrough; and the still further provision of a centrifugal blastingmachine having a throwing wheel with a plurality of peripheral dischargeopenings of graduated crosssectional area so as to concentrate theparticulate material thrown thereby against a particular area of theobject.

The aforementioned and other objects are accomplished in the presentinvention by accelerating the particulate material through a wheelhaving a plurality of radially extending slots which terminate inperipheral discharge openings of different size. Specifically, in thepreferred embodiment the throwing wheel comprises a pair of spacedplates, or discs, one of the discs having a plurality of integral,radially extending vanes disposed between the two discs. The vanesterminate short of the axis of rotation of the wheel so as 'to form acentral space, or inlet, through which the particulate material issupplied. The vanes are spaced from each other by slots which arearranged to receive removable inserts. Each insert has a. blade portionand a relieved portion which cooperates with the upper disc to form aslot. Each slot terminates in a peripheral discharge opening ofdifferent cross-sectional area. A conical insert is disposed in thecentral recess of the wheel for distributing the particulate material tothe several slots therein.

The throwing wheel is drivingly connected to a tubular shaft having aplurality of slots in the lower end thereof which arealigned with theslots in the throwing wheel at a high velocity.

' of pins 21.

The particulate material is supplied to the throwing wheel through astationary tube coaxially disposed within the tubular drive shaft. Thesupply tube is supported by a stationary hopper, and the rate of flow ofparticulate material is controlled by an orifice disposed at thedischarge opening of the storage hopper.

In a modified embodiment, the throwing wheel comprises a pair of spaceddiscs, one of the discs having a plurality of radially extending vanesthereon constituting throwing blades. extending tapered slots whichterminate in peripheral discharge openings of graduated cross-sectionalarea. The slots communicate with a central recess in the wheel withinwhich a conical insert is adjustably supported. By varying the positionof the conical insert the rate of flow of particulate material throughthe wheel can be controlled.

In operation the stationary fixture is suitably attached to a propellerhub, with the throwing wheel disposed within a hub socket having anintegral thread relief machined therein. When shot is supplied to thethrowing wheel, it is accelerated in radial movement as it travelsoutwardly along the throwing vanes, or blades, and is thrown at blastingvelocity by centrifugal force from the peripheral discharge openings ofthe wheel so as to impinge the entire area adjacent the thread relief.However, by reason of the graduated size of the peripheral dischargeopenings the shot is concentrated in the predetermined area of thethread relief and graduated over the other portions of the area adjacentthereto.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein preferred forms of the present invention are clearlyshown.

In the drawings:

Figure 1 is a sectional view of shot peening apparatus constructedaccording to this invention.

Figure 2 is a view, partly in section and partly in elevation takenalong line 2-2 of Figure 1.

Figure 3 is a chart indicating the axial width of the peripheraldischarge openings in the throwing wheel shown in Figure 1. I

Figure 4 is a perspective view of one of the inserts used in thepreferred embodiment.

Figure 5 is a sectional view of a modified embodiment of shot peeningapparatus constructed according to this invention.

With particular reference to Figure 1, the shot peening apparatus isattached to an annular fixture 10 having a recess 11 adapted to receivea socket 12 of a propeller hub. The fixture 10 is connected to asupporting bracket 13 by means of a plurality of bolts 14, the bolts 14also having threaded engagement with a second fixture 15 having a frustoconical flange 16. The propeller hub socket 12 has machined therein anintegral thread relief designated by numeral 17 disposed immediatelybelow a threaded portion 18. A nut 19 engages the threads 18, the nut 19having a frusto conical inner surface for receiving the frusto conicalflange 16 of the fixture 15. In addition, the nut 19 has a flangedportion to which a spacer ring 20 is connected. by a plurality Thefixture 10 is secured to the propeller hub socket 12 by a plurality ofstuds 22 having rounded ends which engage a radiused portion of the hubsocket whereby when the studs 22 are tightened the frusto conical flange16 of the fixture 15 will be forced into wedging engagement with thefrusto conical surface of the nut 19.

The fixture 15 has a central through bore 23 and has mounted therein apair of spaced ball bearing assemblies 24 and 25. The outer races of-theball bearing assemblies The vanes are separated by radially- 24 and 25are maintained in vertically spaced relation by a bearing sleeve 26. Avertically arranged tubular drive shaft 27 is rotatably supported by theball hearing assemblies 24 and 25 in the fixture 15. As shown in Figure1, the upper end of the drive shaft 27 may have attached thereto apulley 28 which receives a belt 29 whereby the shaft 27 can be rotatedby a suitable rotary driver, such as an electric motor, not shown. Thelower end of the shaft 27 is press fitted into a central aperture of anupper disc 39 of a throwing wheel, or rotor, designated gen erally bythe numeral 31. A bushing 48 is interposed between the inner race of theball bearing assembly 25 and the upper surface of the disc 30. The disc30 is drivingly connected with the shaft 27, and the lower end of theshaft 27, and the lower end of the shaft 27 has a plurality of radiallyextending slots 32 therein.

With particular reference to Figure 2, it can be seen that the lower endof the shaft 27 has six equidistantly spaced slots 32 formed therein.One wall 33 of each slot extends on a radius from the axis of the shaft27, and the other wall 34 of each slot is substantially tangential tothe inner diameter of the tubular shaft so as to form a knife edge 35 atits intersection with wall 33 on the inside diameter of the shaft. Theknife edges 35 prevent the particulate material which is fed through theslots 32 from deforming the inside diameter of the shaft which wouldcause clogging and thereby restrict the How of particulate material,such as shot, to the throwing wheel 31. The throwing wheel 31 alsoincludes a lower disc, or plate 36 having a plurality of upstandingvanes 37 formed integrally therewith which maintain the discs 30 and 36in spaced relation. The discs 30 and 36 may be held in assembledrelation by means of set screws 38 which extend through the disc 30 andengage threaded openings in the vanes 37. The vanes 37 terminate shortof the center of the rotor 31 and extend in a substantially radialdirection so as to form a central recess, or inlet, 39 for theparticulate material. In addition, one edge of each vane is beveled asindicated by numeral 49 to coincide with the wall 34 of the slots 32 onthe shaft 27.

The vanes 37 are circumferentially spaced so as to form slots 40therebetween. An insert 41 is removably secured within each slot 40 by apair of set screws 42a.

With particular reference to Figure 4, each insert 41 is substantiallypie-shaped and includes a blade portion 43a and a relieved portion, orgroove, 44a which together with the upper disc 30 forms a slot having aperipheral discharge opening. The peripheral discharge openings areindicated by numerals 42 through 47 in Figure 2. The relieved portions44a of five of the inserts 41 are formed by upwardly inclined, ortapered, surfaces of different slope. The relieved portion 44a of thesixth insert is substantially flat as shown by the left hand insert 41in Figure 1. The axial width of each discharge opening 42 through 47 isdifferent, and thus the cross sectional area of each discharge openingis different. In the particular embodiment disclosed, the axial width asindicated by A in Figure 1 of the discharge opening is shown in thechart of Figure 3, from which it can be seen that the axial width of thedischarge opening 42 is .125, and the axial width of each successivedischarge opening increases by .075.

As seen in Figure 1, a central insert 50 for distributing the shot tothe several slots in the rotor is disposed within the central recess 38of the rotor. The insert 50 is substantially cone-shaped as seen inFigure 1 and is secured in place by a bolt 52. The particulate materialis supplied to the central recess 39 of the rotor through a stationarytube 53 coaxially disposed within the tubular drive shaft 27. The'upperend of the stationary tube 53 is suitably attached to a stationarystorage hopper 54, having a removable orifice insert at the dischargeopening thereof, By substituting inserts 55 having different sizeorifices, the rate of flow of a particulate material 4 from the hopper54 into the supply tube 53 can be varied and controlled.

Operation of the preferred embodiment of the centrifugal shot peenin-gapparatus is as follows. As the particulate material is fed through thehopper 54 it flows through the orifice of the insert 55 and fallsthrough the vertical supply tube 53. The particulate material drops onthe cone-shaped insert 50 carried by the rotor 31 and is distributedthereby through the slots 32 in the lower end of the drive shaft 27. Theparticulate material is then picked up by the blades 43a of the rotorand thrown outwardly by centrifugal force due to rotation of the rotor31 so as to impinge the area adjacent the thread relief designated bynumeral 17 of the propeller hub socket 12. However, by virtue of thefact that the discharge openings 42 through 47 in the rotor are ofdifferent cross-sectional area, or of graduated size, the particulatematerial thrown by the rotor 31 is concentrated in the area of thethread relief 17. Thus, the shot peening apparatus automaticallyselectively work hardens the thread relief area so as to concentrate thework hardening in the thread relief and graduate the work hardening onother portions adjacent this area.

With particular reference to Figure 5, a modified embodiment of a shotpeening apparatus constructed according to this invention will bedescribed, similar numerals depicting similar parts as described inconjunction with the preferred embodiment. In the modified embodiment,the rotor comprises an upper disc, or plate, 61 and a lower disc, orplate 62 suitably connected thereto. The lower disc 62 is formed with aplurality of integral vanes, or blades, which form slots 63therebetween. The slots 63 likewise terminate in peripheral dischargeopenings, such as indicated by numerals 64 and 65, of differentcross-sectional areas. As in the preferred embodiment, the rotor 60 canbe formed with six radially extending slots which terminate in dischargeopenings of graduated cross-sectional area such as shown in the chart ofFigure 3. The axial width of the discharge openings in the rotor 60 isdetermined by the inclination of the lower surface of each slot machinedin the disc 62.

In the modified embodiment the drive shaft 66 has a plurality of slots67 spaced inwardly from the lower end thereof, each slot connecting withone of the slots 63 in the rotor 60. The lower end of the drive shaft 66is press fitted into the disc 60 and has a threaded portion arranged toreceive a screw 68 having a conical end portion 69 disposed within thetubular shaft 66. The screw 68 can be adjusted relative to the driveshaft 66 to control the flow of particulate material from the interiorof the drive shaft 66 through the slots 67 to the central area 70 of therotor 60. After the screw 68 is adjusted to obtain the desired rate offlow, it is locked into position by a nut 71. Operation of the modifiedembodiment is substantially the same as that of the preferred embodimentin that particulate material supplied to the drive shaft 66 is thrownoutwardly by the rotor and impinges the area adjacent the thread relief17 of the hub socket 12 with the particulate material being concentratedin the thread relief.

From the foregoing it is readily apparent that the present inventionprovides centrifugal blasting apparatus wherein the particulate materialthrown by the apparatus can be concentrated at a particular portion ofthe area in which the particulate material is distributed. In thismanner where the apparatus is used to work harden an object, differentareas of the object can be work hardened to difierent degrees with thedegree of work hardening being graduated from an area of maximum workhardening.

While the form of embodiments of the invention as herein disclosedconstitute preferred forms, it is to be understood that other formsmight he adopted, as may come within the scope of the claims whichfollow.

What is claimed is as follows:

1. A centrifugal blasting machine designed for throwing particulatematerial at blasting velocities including, a rotatable throwing wheelhaving a plurality of radially extending vanes terminating short of theaxis of rotation to form a center inlet, said vanes having slotstherebetween which terminate in peripheral dischmge openings in saidwheel, each peripheral discharge opening being of differentcross-sectional area, and means for feeding particulate material intothe center inlet of said wheel whereby the particulate material thrownfrom said wheel will be distributed over a path of predetermined areawith a concentration at a portion of the area of said path.

2. A centrifugal blasting machine designed for throwing particulatematerial at blasting velocities including, a rotor mounted for highspeed rotation including a plurality of spaced throwing vanes extendinginwardly toward the axis of rotation, said vanes having slotstherebetween which terminate in circumferentially spaced peripheraldischarge openings in said rotor, each discharge opening having adifferent cross-sectional area, and supply means for particulatematerial communicating with the inner ends of said slots whereby theparticulate material thrown from said wheel will be distributed over apath of predetermined area with a concentration at a portion of the areaof said path.

3. A centrifugal throwing wheel comprising, a pair of spaced discshaving a plurality of radially extending particulate material propellingvanes therebetween, said vanes having slots therebetween which terminatein peripheral discharge openings, each discharge opening being ofdifferent cross sectional area whereby the particulate material thrownfrom said wheel will be distributed over a path of predetermined areawith a concentration at a portion of the area of said path.

4. A centrifugal throwing wheel comprising, a pair of spaced discshaving a plurality of radially extending particulate material propellingvanes therebetween, said vanes having slots therebetween, and aremovable insert secured in each slot, eac h insert having a bladeportion and a groove which forms a peripheral discharge opening, eachperipheral discharge opening being of different cross-sectional areawhereby the particulate material thrown from said wheel will bedistributed over a path of predetermined area with a concentration at aportion of the area of said path.

5. A centrifugal blasting machine designed for throwing particulatematerial at blasting velocities including, a rotatable throwing wheelhaving a plurality of radially extending vanes terminating short of thecenter of said wheel to form a center inlet, said vanes having slotstherebetween which terminate in peripheral discharge openings in saidwheel, each peripheral discharge opening being of differentcross-sectional area with the crosssectional area of said dischargeopenings being graduated around the periphery of said wheel, a tubularshaft supporting said wheel and having a plurality of slotscommunicating with said center inlet, and means for feeding particulatematerial into said tubular shaft whereby the particulate material willbe thrown from said wheel and distributed over a path of predeterminedarea with a concentration at a portion of the area of said path.

6. A centrifugal blasting machine designed for throwing particulatematerial at blasting velocities including, a rotatable throwing wheelhaving a plurality of radially extending vanes terminating short of thecenter of said Wheel to form a center inlet, said vanes having slotstherebetween which terminate in peripheral discharge openings in saidwheel, each peripheral discharge open ing being of ditferentcross-sectional area, a tubular shaft supporting said wheel and having aplurality of slots therein communicating with said central inlet, saidslots having intersecting tangential and radial walls forming knife-likeedges on the inside diameter of said tubular shaft, and means forfeeding particulate material into said tubular shaft whereby theparticulate material will be thrown from said wheel and distributed overa path of predetermined area with a concentration at a portion of thearea of said path.

7. The centrifugal blasting machine as set forth in claim 6 wherein saidlast recited means comprises a stationary tube coaxially disposed withinsaid tubular shaft.

8. A centrifugal blasting machine designed for throwing particulatematerial at blasting velocities including, a rotatable throwing wheelhaving a plurality of radially extending vanes terminating short of thecenter of said wheel to form a center recess, said vanes having slotstherebetween which terminate in peripheral discharge openings in saidwheel, each peripheral discharge opening being of differentcross-sectional area, a cone-shaped insert disposed within said centralrecess, and means for supplying particulate material to said centerrecess, which particulate material is distributed by said insert andthrown from said wheel so as to be distributed over a path ofpredetermined area with a concentration at a portion of the area of saidpath.

9. A centrifugal blasting machine designed for throwing particulatematerial at blasting velocities including, a rotatable throwing wheelhaving a plurality of radially extending vanes terminating short of thecenter of said wheel to form a center recess, said vanes having slotstherebetween which terminate in peripheral discharge openings in saidwheel, each peripheral discharge opening being of differentcross-sectional area, a conical insert disposed in said center recess, atubular shaft supporting said wheel and having a plurality of slotscommunicating with the inner ends of the slot in said wheel, and meansfor supplying particulate material to said wheel through the slots insaid shaft whereby the particulate material thrown from said wheel willbe distributed over a path of predetermined area with a concentration ata portion of the area of said path.

10. The centrifugal blasting machine set forth in claim 9 wherein saidconical insert is adjustably supported in said wheel within said tubularshaft so as to control the rate of flow of particulate material throughthe slots in said tubular shaft.

11. A centrifugal blasting machine designed for throwing particulatematerial at blasting velocities including, a rotatable throwing wheelhaving a plurality of radially extending vanes terminating short of thecenter of the wheel to form a center inlet, said vanes having slotstherebetween which terminate in peripheral discharge openings in saidwheel, and means for feeding particulate material into the center inletof said wheel, said peripheral discharge openings being of differentcross sectional area so that the particulate material thrown from saidwheel will be distributed over a path of predetermined area with aconcentration at a portion of the area of said path.

References Cited in the file of this patent UNITED STATES PATENTS2,507,166 Lehman -5. May 9, 1950 2,532,136 Zahn Nov. 28, 1950 2,765,588Puhr-Westerhide Oct. 9, 1956 FOREIGN PATENTS 242,941 Germany Jan. 26,1912

